By the argument of your first paragraph, Android and iOS are no threat to Windows because they don't run Windows apps. But of course they are, just as Samsung

By the argument of your first paragraph, Android and iOS are no threat to Windows because they don't run Windows apps. But of course they are, just as Samsung is a threat to Apple, Apple is a threat to Samsung, etc. We are doing a set of tasks and using features and functions that multiple options provide a solution for. Platform tie-in was once a strong bond, but has dramatically weakened. Those people who chose teams in the nascent days might be somewhat locked in, but anyone picking a platform over the past half decade has almost always created a transferable world. As a case in point, my wife recently went from a Nexus 5 to an iPhone. Virtually nothing in her life changed: She still had gmail and the KFC app and Facebook and Hangouts and a good, standards compliant web browser and SMS, etc. For a variety of reasons she decided she didn't like idioms of the OS so she moved to a Galaxy S8, and again her world was close to identical.